In aircraft, extraction is often used to dehumidify the cabin air owing to electronic devices as well as the insulation and structure of the aircraft. The comfort limit for crew and passengers with regard to humidity as a rule is at least a relative share of 30%, while this share can only measure 1 to 2% at an altitude of 40,000 feet. Under certain conditions or flight operations, a preceding increase in the oxygen concentration in the breathable air of the flight crew or so-called loadmaster is necessary. As a rule, this so-called pre-breathing is necessary over a longer period to sufficiently elevate the oxygen concentration in the blood. The use of breathing masks over this long of a period is not comfortable enough in many instances. By contrast, a free oxygen jet with negligible moisture would increase wearing comfort, but cause the mucous membranes exposed to the jet to dry out in comparatively short order.